Tannin exists broadly in the plants and has many phenolic hydroxyl groups in the molecule. Tannin is classified into a hydrolyzable tannin that is hydrolyzed with acid, alkali or tannase, and a condensed tannin that is not hydrolyzed. It is known that the condensed tannin includes a simple condensed tannin (proanthocyanidin) which is composed of constitutive flavan-3-ol units and a complex condensed tannin which is composed of constitutive units of flavan-3-ol, caffeic acid and chalcone-.beta.-ol.
It is known that such a condensed tannin has a hair-protecting effect (see Japanese Published Examined Patent Application No. 37884/90). However, the effect is exclusively exerted on the surface of hair as the effect of a cosmetic, and the hair-growing effect of the condensed tannin is unknown. Proanthocyanidin is utilized as an antioxidant (see Japanese Published Unexamined Patent Application No. 16982/86), but the hair-growing effect of proanthocyanidin is unknown.